The number of people sickened in France's outbreak of locally acquired chikungunya has grown from 2 to 13, all of them in the Provence-Alpes-Cote d'Azur region in the south who were sick during the first half of August, the World Health Organization (WHO) said in an Aug 25 statement.

In the Americas, the number of chikungunya cases surged last week, but most of the more than 30,000 new infections reflect catch-up reporting by Brazil, the most-affected country by far this year.

Outbreak at French tourist destination

The 13 infections in France include 4 confirmed, 1 probable, and 8 suspected cases, all involving patients ages 3 to 77 years old from Cannet des Maures commune in the region's Var department, according to the WHO.

Last week the European Centre for Disease Prevention and Control (ECDC) noted a local cluster of two cases in its weekly communicable disease threat report. It added that Aedes albopictus mosquitoes, which can carry the virus, are established in the south of France and in parts of other European countries and that more local clusters this time of year wouldn't be surprising.

In its statement, the WHO said a pair of local chikungunya cases were reported in the same part of France in 2010 and that 11 cases were reported in Montpellier in 2014.

"Nevertheless, chikungunya is an emerging disease in southern Europe, and an outbreak is considered unexpected," the WHO said, reiterating that Ae albopictus is establishing itself in a large part of the Mediterranean basin and beyond.

The area in which the new local cases were reported is a popular tourist destination, especially in the summer, and is close to the border with Italy, which also has established populations of Ae albopictus mosquitoes.

Last week the ECDC said the cluster didn't seem to have any link to imported human cases. The WHO said in its statement that an entomological investigation on Aug 10 confirmed Ae albopictus in the affected area and that blood collections there have been temporarily halted.

Brazil cases boost Americas totals

Meanwhile, affected countries and territories in the Americas reported 31,454 more chikungunya cases, most of them in Brazil, which reported 6 weeks' worth of cases to the Pan American Health Organization (PAHO), the agency said in an Aug 25 update.

Brazil now has 104,298 confirmed cases for the year, along with 58,837 suspected cases, for a total of 163,135, or 94% of the 2017 total in the region. Brazil also reported 24 more deaths from chikungunya, lifting the number of fatalities from the disease this year to 75.

Other countries reported much smaller numbers of new cases include El Salvador, Nicaragua, Bolivia, Colombia, and Peru. So far this year the Americas region has reported 172,912 suspected, confirmed, and imported chikungunya cases.

Since the Americas outbreak began in 2013 in the Caribbean, the region has now reported 2,559,623 cases.